This Is How Parked Electric Cars Are Earning Money in Denmark

They're basically battery packs on wheels.

What if your parked car could earn money? Vehicle-to-grid (V2G) systems allow electric cars to discharge electricity back into the grid, and a yearlong trial in Denmark is showing how owners can use that ability to generate cash. A fleet of Nissan e-NV200 vans is earning about 1,300 euros ($1,530) a year with V2G, Francisco Carranza, Nissan Europe director of energy services, said in a recent interview with Bloomberg. The trial is being conducted by Nissan and Italian utility Enel SpA.

V2G not only provides electric car owners with a potential way to make money; it also addresses an issue many utilities are concerned about. Utilities already have to work to "balance" their electricity grids, ensuring power is produced at a consistent rate despite peaks and drops in demand. The rise of renewable energy may make that more difficult, since sources like wind and solar produce electricity less consistently.

But a V2G system could allow electric cars to absorb any extra electricity produced by wind or solar sources during periods of low demand, and discharge it back into the grid when demand increases. It's a similar concept to the stationary energy-storage battery packs marketed by Tesla and other companies, but applied to cars. Those cars essentially become mobile energy-storage units.

This idea isn't new. The University of Delaware and even the U.S. Air Force have experimented with V2G. But don't expect the power company to pay you for plugging an electric car into the grid just yet. Electric cars currently in production can draw power from the grid to charge their battery packs, but they can't reverse the process. Automakers could add hardware to enable V2G, but they probably won't until they see a clear demand for it from customers. And that likely won't happen until electric-car owners can actually earn money from V2G.

Managing fleets of electric cars connected to the grid poses significant challenges. Utilities will have to coordinate charging and discharging, ensuring that the grid remains balanced and that drivers don't get stuck with drained batteries. In the United States, at least, regulations may need to be revised as well. If those hurdles can be cleared, V2G could be a big boost for electric cars.